AudioCircle
Industry Circles => Audio by Van Alstine => Topic started by: avahifi on 9 Sep 2013, 06:35 pm
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The AVA Vision RIAA Phono Preamplifier
The Vision Phono Preamplifier is a brand new direct coupled split passive EQ very high performance solid-state phono preamp with high current buffered output circuits to handle long cables, complex tape loops, and other difficult loads.
It is based on reaching way back into our archives, back to the Jensens Stereo Shop days of the 1970s, to revisit a schematic I drew then. The original never saw production because the integrated circuits of those days just were not quiet or linear enough. In addition, trying to null DC offset took trimming resistors for each IC and that would have been a nightmare in production.
However, there was lots of promise in that old circuit so I examined it again recently and we bread-boarded it up once more, but this time with much better modern ICs and more.
Rethinking the design further, I realized we did not need the third amplification stage, just a much better choice, an outstanding current buffer to isolate the second passive EQ section from the real world. Then we spent weeks testing and listening to almost all the modern linear ICs available, some even surface mount chip types. We finalized the design with National LME49710 front end ICs and the very expensive Burr-Brown OPA627 ICs for the second stage. This combination provides the low noise and grain free outstanding dynamic range we demand. We never considered dual ICs because of their higher crosstalk and distortion issues.
Because the integrated circuits we selected have very low DC offset or drift, all coupling capacitors have been eliminated from the signal path. The Vision Phono Preamplifier is direct coupled from input to output. Because the linear ICs are driven to unity gain at DC, you have no worries about which brand or type of coupling capacitors to use, there are none. The two capacitors in the passive EQ sections are select polypropylene types. There is plenty of raw power supply built into the Vision board itself, along with careful supply decoupling directly at each active device power supply rail feed.
In our 17 inch wide chassis, the power transformer and high current plus and minus 15 volt regulated power supply board can be kept far from the active circuits to reduce noise even more.
In addition to the free standing Vision Phono Preamp, the new Vision Phono Preamp is available right now as an option that can be built into all new AVA preamplifiers.
It is also available as an outstanding upgrade to the phono sections of almost any older AVA preamplifier.
If you own a preamplifier without a phono section and now you wish you could have great RIAA phono performance without starting over again or spending a fortune, we have just what you need, an Audio By Van Alstine RIAA Phono Preamp. Or consider replacing the harsh and lumpy phono section of your present receiver or preamp with one of these musical gems.
The AVA Vision RIAA phono preamp is suitable for any normal output phono cartridge, head amp, or moving coil step-up transformer. It comes packaged in our rock solid 17" wide x 12" deep x 3.5" high chassis. It has gold plated phono inputs, gold plated line outputs, and a lighted power switch. Connect the Vision Phono Preamp to your line preamp or receiver and enjoy records all over again.
Call me for more details. It is available right now. 651-330-9871
Frank Van Alstine
(http://www.audiocircle.com/image.php?id=86731)
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Oh yes, prices.
Complete factory wired Vision phono preamp in AVA standard 17" wide chassis with black faceplate: $599
The big AVA chassis is pretty expensive, made in the USA, not in China.
Installed option in any new AVA preamplifier: $249
Retrofit into almost any older AVA preamplifier, either now with or without older phono circuits: $349
It could be doable as a do it yourself kit, just add a quiet plus and minus 15V power supply. One catch, its a bit tricky to install the five lead LME49600 surface mount current buffers. Do you think you are up to that?
Frank
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I auditioned this phono preamp (and had a visitor (Frank)) over the Labor Day weekend. For $600, it is a big player, with a solid bass line, extended high end (excellent cymbal crash) and a nice and wide sound stage. Of course, it's also built like a brick shit house, but that is the usual thing at AVA. I found that it had a very nice gain with 2.5mv HOMC cartridges (like my Sumiko BPS), but had ample head room for both the AT440MLa, and Grado Gold1.
In fact, Frank and I did some listening with a Grado Green1 mounted to my AR-XA table, with excellent sonic results. Lack of hum and excellent dynamic attack made listening to Andreas Vollenweider's White Wind a sonic adventure, for sure.
Wayner
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What is the capacitive loading on the new Vision phono preamp?
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Oh yes, prices.
It could be doable as a do it yourself kit, just add a quiet plus and minus 15V power supply. One catch, its a bit tricky to install the five lead LME49600 surface mount current buffers. Do you think you are up to that?
Frank
You can completely circumvent any problems that newbie diy'ers may have with surface mount components, by selling the boards with the buffers installed. Just price accordingly.
Best,
Anand.
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We do not provide for additional capacitive loading built into our phono preamplifiers.
Essentially capacitive loading at the front end of a phono preamp is used to create an underdamped resonant peak in the cartridge frequency response above the audio range to lift its measured response in the upper audio range to appear to be flatter.
However, one poorly understand electronic fact is that resonator circuits resonate. They generate output at and near their tuned frequency and also when they see harmonics of their tuned frequency. Thus cartridge mistracking and out of band garbage makes them susceptible to generating "splashes" of wide band garbage in and out of the audio range which can overload circuits downstream.
We suggest you are better off just dealing with the natural built in roll off of your phono cartridge at high frequencies then trying to fix it with additional capacitive loading.
On reason we have always favored Grado phono cartridges is because their coil inductance is much lower than that of the typical moving magnet cartridge and thus is much less affected by cable capacitance and have an excellent frequency response without capacitive help.
Regards,
Frank Van Alstine
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We are still looking for an AC member in the Minneapolis/St.Paul area who would like to hear this new phono preamplifier and a new prototype vacuum tube hybrid phono preamp too.
Call me at 651-330-9871 if you are interested.
Frank Van Alstine
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If you have a preamp with a phono section, where would you plug this in?
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If you have a preamp with a phono section, where would you plug this in?
If your preamp has already a phono,you can replace it with this(better not do it if not qualified),you can use it as stand alone phono preamp stage plug the phono outputs from the turntable into the phono inputs of the phono preamp and plug the outputs of the phono preamp into line level imputs of the line preamp... :thumb:
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We are still looking for an AC member in the Minneapolis/St.Paul area who would like to hear this new phono preamplifier and a new prototype vacuum tube hybrid phono preamp too.
Call me at 651-330-9871 if you are interested.
Frank Van Alstine
Frank after being a customer for over 10 years I can see this coming. So since I can not afford the new Fet-Valve CF pre at this time I'll wait until the new tube phone stage is ready as an option for nthe new pre then place my order.
Can't wait
Ric
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The prototype vacuum tube hybrid phono preamp we are working on will not be available as a built in option in any new AVA preamplifier, only as a separate free standing unit It uses four tubes and four exicon power mosfets, along with eight high voltage regulated power supplies, two regulated low voltage power supplies, and oh yes, all the parts necessary for exact passive RIAA network and support structure.
It takes a large mother board all by itself. We would need to do a double-decker preamp, 7 inches high, with stacked PC cards and fan cooling to get it all in one box along with a great tube line preamplifier.
The optional new Vision solid state split passive EQ phono preamp described above is the one now available built into either the new T9 or Fet Valve CF preamps. It is pretty stunning in its own right.
Frank
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We now have completed and tested an adjustable moving coil version of our new Vision phono preamplifier.
This version allows you to set MC gain up or down 6 dB from MC standard, adjust input loading from 47 ohms to 1400 ohms in five steps, and switch it back to standard moving magnet operation too. This is all done with a ten position DIP switch per channel.
Installed option in any new AVA preamplifier is $329.
Musically it is simply spectacular!
Frank Van Alstine
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New amazing AVA Phono Preamplifier Options:
We now can supply any new AVA preamplifier with three choices of our new ultra high performance Vision RIAA phono preamplifiers.
The basic split passive EQ moving magnet phono section is $249 installed. We can set this specifically for your phono cartridge upon request.
The basic split passive EQ moving coil phono section is $299 installed. We can set the gain and cartridge loading specifically for your cartridge upon request.
Newest, and the best yet is our new adjustable and flexible universal phono section. Using a ten position gold contact dip switch per channel, this option can be easily user set for either moving magnet or moving coil use. The moving coil gain is adjustable as is moving coil cartridge loading. This is the best yet execution of our great new split passive EQ phono section. The cost is $329 installed in any new AVA preamp.
These phono sections can also be retrofitted in most older AVA preamplifiers for $50 extra cost.
Please call us for details. We guarantee satisfaction.
Frank Van Alstine
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Hi Everyone
Frank offered to retrofit my preamp with the new phono board, and I've had it here long enough to do some critical listening. Unfortunately, I don't own a lot of high-quality vinyl, a fact that the new preamp made pretty obvious. But those few good recordings I do have (A Mercury Living Presence recording of the Detroit Symphony from the late 50's, some vintage RCA gold seal recordings of the Philadelphia Orchestra) sound gorgeous. The phono stage just provides a clearer window into the recording, and when the recording engineers weren't twiddling with too much EQ or using too
many mics, or things didn't get messed up at the pressing stage, the result is very gratifying. It's enough to get me to pay top dollar for more of the really good classical LP's out there. Thanks Frank! Dennis Murphy
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Yesterday, I took delivery of my second AVA piece, a phono preamp. My first is a Humdinger. This new phono preamp replaces the the phono section of my Emotiva USP-1. I didn't plan on getting this now since I just got a new turntable in October, but the sale hooked me last month.
In October, I purchased a George Warren that was in RMAF. If you were there, I got the one that is piano black. Since I haven't had a table for about 15 years, it easy to understand why I wasn't in a hurry to get this preamp. I haven't even reacquainted myself with my entire vinyl collection. This is my last turntable, but not my last tonearm or cartridge.
While I knew that this would be better than the Emotiva, I've just got another record collection to replace the one that I rediscovered when I got the George Warren.
Patrick
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Using a ten position gold contact dip switch per channel, this option can be easily user set for either moving magnet or moving coil use. The moving coil gain is adjustable as is moving coil cartridge loading.
Frank Van Alstine
Does this require opening the preamp to adjust or are the switches accessible from outside the unit?
Paul
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You do need to remove the cover to set the switches for your particular phono cartridge.
We consider this to be a semi-permanent adjustment task, only needed if you change cartridges.
No way to provide direct access on our preamp mother boards or in our full size chassis.
Merry Christmas,
Frank
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Yesterday, I took delivery of my second AVA piece, a phono preamp. My first is a Humdinger. This new phono preamp replaces the the phono section of my Emotiva USP-1. I didn't plan on getting this now since I just got a new turntable in October, but the sale hooked me last month.
In October, I purchased a George Warren that was in RMAF. If you were there, I got the one that is piano black. Since I haven't had a table for about 15 years, it easy to understand why I wasn't in a hurry to get this preamp. I haven't even reacquainted myself with my entire vinyl collection. This is my last turntable, but not my last tonearm or cartridge.
While I knew that this would be better than the Emotiva, I've just got another record collection to replace the one that I rediscovered when I got the George Warren.
Patrick
It's now been about a month since I got my new phono preamp. My new AVA is a huge improvement over my Emotiva! No surprise there! Not only can I hear more coming thru my Salk Songtowers, it has a lot more texture from top to bottom. I can now feel the bass on some songs in my listening chair, which didn't happen before. Since the soundstage seemed to be wider, I took out some of the toe in on my speakers.
It's pretty safe to say that Emotiva preamp is the next thing that will be replaced in my system. And it will be a AVA!
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We finally got all the new chassis metal delivered and here is the new Vision phono preamp in its proper compact case and at a lower price as well. $499.
Check it out here:
http://avahifi.com/index.php?option=com_content&view=article&id=179&Itemid=237
Its all made in the USA too, of course.
Frank Van Alstine
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We now have completed and tested an adjustable moving coil version of our new Vision phono preamplifier.
This version allows you to set MC gain up or down 6 dB from MC standard, adjust input loading from 47 ohms to 1400 ohms in five steps, and switch it back to standard moving magnet operation too. This is all done with a ten position DIP switch per channel.
Installed option in any new AVA preamplifier is $329.
Musically it is simply spectacular!
Frank Van Alstine
Frank,
How is this project work out? Thanks
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The Vision phono preamp project has worked out great.
There are three very very positive reviews available. Just go to our Fet Valve CF page at our web site, www.avahifi.com and read the reviews of this preamplifier. The Vision phono preamp was built into all of these preamps that were reviewed and the phono section got great mentions in each of these reviews.
We can ship the preamp in the new compact chassis right now. Price $499.
Frank
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The prototype vacuum tube hybrid phono preamp we are working on will not be available as a built in option in any new AVA preamplifier, only as a separate free standing unit It uses four tubes and four exicon power mosfets, along with eight high voltage regulated power supplies, two regulated low voltage power supplies, and oh yes, all the parts necessary for exact passive RIAA network and support structure.
It takes a large mother board all by itself. We would need to do a double-decker preamp, 7 inches high, with stacked PC cards and fan cooling to get it all in one box along with a great tube line preamplifier.
The optional new Vision solid state split passive EQ phono preamp described above is the one now available built into either the new T9 or Fet Valve CF preamps. It is pretty stunning in its own right.
Frank
Franks,
My bad, I mean this project.
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The Vision split passive EQ solid state preamp, with a few final design improvements turned out to be better then the best tube phono section we have yet done. It is quieter, more dynamic, more transparent, takes one hell of a lot less real estate, and is way less expensive, even after we switched to all OPA627 devices in it (a hundred dollars worth of active devices not including the LME49600 output buffers). There are over 300 hand done solder connections on the audio board alone.
Of course we save a few dollars on capacitors - - - there are none in the direct signal path at all, no $200 Russian beeswax uranium coated capacitors left over from WW2 and no $100 fuses in it either.
Price to performance ratio, it is a steal.
Frank
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no $200 Russian beeswax uranium coated capacitors left over from WW2 and no $100 fuses in it either.
:rotflmao:
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Views:
(http://www.audiocircle.com/image.php?id=119133)
(http://www.audiocircle.com/image.php?id=119134)
'ner
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I really like the look. Very nice!
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What are the gain settings for this unit? Have a 10x5 homc. Thanks!
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40 dB gain for normal MM cartridges.
Switchable 54 dB, 60 db, and 66 dB gain for MC cartridges.
MC load settings from 30 ohm to 1K ohm with many settings in between.
Frank
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What are the gain settings for this unit? Have a 10x5 homc. Thanks!
Your HOMC is designed to work on a MM input.
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Right but for some reason 40 dB does not seem to be enough gain in my system. Could be a problem somewhere else in the vinyl chain. My Jasmine has a really high 55 dB of gain on the mm side and I need every bit of it.
Lately I've had to crank it higher that usual to get a decent volume level. CD's sound awesome so I'm not sure if it's the phono amp, the phono cable (the ground wire came loose from the spade on the stage end) or what.
On the AVA I'm thinking the lowest gain on the mc side at 1kohms might work best with the 10x5?
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Well, I believe that cart is designed for a 47K ohm load. I think its output is rated at 2.5mv, just like my Sumiko BPS. It should be almost a non issue with the 40db of gain on the MM setting. I'm afraid 54 db of gain may overload your line preamp with some program material. The next question is, are you sure your current preamp is putting out even 40 db of gain on its mm side? Why would Jasmine make an MM preamp with 55db of gain? That is simply too much for almost all MMs.
Wayner
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The 10x5 is supposed to be 47k or less. I've read it sounds best at 1k. I've tried a Bellari at 36 dB and a used bugle, both too low.
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OK, that's quite a load change from 47K to 1K. To me, the 55db of gain should be over-modulating your whole line preamp. Perhaps the 10 X 5 isn't really putting out even 2.5mv......
I don't know. Sounds goofy.
Wayner
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I agree but have heard of other stages with high amounts of gain on mm side. Something is not right in that area of my rig.
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OK. I'm just worried that the 1K ohm load will kill your high end frequency response if you chose to go to the MC side.
'ner
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Is there any way this phono preamp could be "hybridized" to allow it to drive an amp directly? Phono stages with a volume pot are rare beasts.
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Sure, that's an easy one for us.
Just order any new AVA preamp with the Vision phono preamp option. It will do a great job of driving any power amp.
Seriously, for the phono section to drive a power amp directly we would have to tool a new version with a volume control and a line stage after the volume control. Even if we did this, the only cost savings over one of our great standard preamps would be the cost of a few switches and jacks. All the support structure would still need to be there. On a one off basis this would cost much more than a Vision preamp with the built in Vision phono section.
Extra functions added for special purposes don't come without all the design, tooling, and fabrication to make them happen. On a one off basis the design, tooling, and set up charges would be exorbitant.
Frank Van Alstine
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Thanks
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Your new, small chassis Vision Phono Preamp looks great! It is a rare treat to have something that is better, and costs less. You should be able to sell a ton of these :thumb:
I hope to buy one soon.
Bill
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As I said in the above post, my next piece will be a new preamp. Later today, a new T10 preamp will be delivered. My AVA phono preamp was traded in, and the Emotiva will be sold. Another new record collection, but I'm not going to spend a dime on new vinyl! :hyper:
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I just found out that the Absolute Sound's review was posted online. Here is the link.
http://www.theabsolutesound.com/articles/audio-by-van-alstine-vision-phonostage/
Mary